Diagnosing a system that won't boot/post

I put together a system recently using some new parts and some old, however it will not boot/post. Basically the monitor fails to receive a video signal (at least I think), since the monitor stays in stand-by mode, or something like that.

Instead of dealing with a very specific diagnosis of my system, I would also like to ask some more general diagnostic questions for several reasons:
1) To understand the reasons behind things -- if I know that, I can figure out how to diagnose the system myself.
2) If I were to get a job at a local computer builder's store, this might be beneficial.

Anyways, I was wondering about some things:

Q - What parts are needed in order for the monitor to at least receive a video signal (the part before the ram check).
>I assume the power, motherboard, and video card have to be working.
>What about the CPU? If it's broken, will you get a signal? If you just have no CPU installed, will it get a signal?
>What about the RAM? If the RAM is broken, will you still get a signal? If there is no RAM, will you get a signal?

Q - What parts are needed in order for the internal speaker to at least work? I glanced at the thread that talks about various ways to diagnose problems based on the speaker noises.
I assume, the power supply and motherboard must be working. However, I also read (probably in a post by someone at another forum) that the processor must work because it is what makes the internal speaker work, is this correct?
>What about RAM? If the RAM is broken, will the internal speaker at least still make a noise? If there is no RAM will it make a noise?

<P ID="edit"><FONT SIZE=-1><EM>Edited by KevinAr18 on 02/04/05 04:00 PM.</EM></FONT></P>
6 answers Last reply
More about diagnosing system boot post
  1. Uhhh take it easy...too many questions.

    First of all when you post with this type of problem U must list all the components of the system U R talking about.

    List what is new and what is old in separate columns.

    I did had the same problem U have and almost went crazy. Until I realize that the connections I made were not done properly. Once I made the proper connections (specially the power cable to the video card and the cables to the Hard drive and optical devices) I turn the machine ON again and still ...nothing...same problem...no video signal.
    The trick was then to turn off the machine and TEAK..unplug and plug again every connection until I noticed that there was one connector that did not go all the way in.....
    So...I turn the machine ON and BINGO...I had the BIOS screen in front of me...the rest is history.

    This doesn't mean you are in the same situation. There are too many variables to consider. First list your components.
  2. A great place for you to start, would be to read the post at the top of this forum. It is very informative. A few answers- yes, no , only if you hold your mouth right.
    Different mobos treat errors diferently. There are some general truths. You need only a psu, and a mobo to get something out of a system speaker (okay, a speaker as well).
    If there is a short anywhere in your system, the psu will imediately shut itself off. In that case, you dont have what is needed to get something out of the speaker.
    A lot of mobos have a post reporter, which is a voice that tells you if you have no cpu, ram or if you have let the tea steep to long (well, maybe not the last, but I've heard they are working on that.)
    The rest use a simple beep code. A medium length beep means everything is fine.
  3. The only reason a system won't make a beep at all is if it doesn't initialize the CPU. That can be caused by a few things, but the most common are 1.) you have a board that uses a 4-pin ATX12v connector, but the power supply doesn't have it, or you didn't connect it 2.) You're using an old unkeyed IDE cable, and it's connected the wrong way.

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  4. Does the IDE cable prevent the CPU from intializing? I thought that you could plug in the IDE wrong and the system will still boot (I've had my IDE Hard Drive not get recognized quite a few times) but I got a monitor signal and probably could boot via other means if I wanted.

    Or do you just mean you won't get a beep, irrespective of the fact that in some case you might get a monitor signal and can boot, and in some cases you might not get a monitor signal?
  5. If something is connected wrong or some device is seriously defective (even a USB device you forgot to disconnect) it can be a showstopper.

    Common culprits also include something not 100% inserted in a slot (VGA, PCI, RAM) so that a pin shorts two leads.

    Without memory your motherboard should beep forever.
    You also get a different beep without a video card.

    Motherboards don't always beep when they should. I have seen motherboards what would do nothing without RAM rather than give the no RAM beep code listed in their manuals.

    I would remove and disconnect everthing, then connect the CPU (& its fan), powersupply, case switches and internal speaker, AND NOTHING ELSE.

    See if you get any beeps.

    Then add the RAM and see if you get beeps. Be 100% certain it is inserted correctly.

    Then add the video card and see if you get any beeps. Be 100% certain it is inserted correctly.

    Also are you sure you mounted the motehrboard correctly. Many times I have been asked to help someone after a bad build only to find they didn't use any spacers and their motherboard was shorting against the case!

    I usually try POSTing with the motherboad on a piece of cardboard prior to mounting it.
  6. Yes, having an IDE cable on backwards can prevent BIOS from doing anything (including starting the CPU).

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